A simple TCP redirector in python

SimpleTcpRedirector.py

#!/usr/bin/env python

import socket
import threading
import select
import sys

terminateAll = False

class ClientThread(threading.Thread):
	def __init__(self, clientSocket, targetHost, targetPort):
		threading.Thread.__init__(self)
		self.__clientSocket = clientSocket
		self.__targetHost = targetHost
		self.__targetPort = targetPort
		
	def run(self):
		print "Client Thread started"
		
		self.__clientSocket.setblocking(0)
		
		targetHostSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
		targetHostSocket.connect((self.__targetHost, self.__targetPort))
		targetHostSocket.setblocking(0)
		
		clientData = ""
		targetHostData = ""
		terminate = False
		while not terminate and not terminateAll:
			inputs = [self.__clientSocket, targetHostSocket]
			outputs = []
			
			if len(clientData) > 0:
				outputs.append(self.__clientSocket)
				
			if len(targetHostData) > 0:
				outputs.append(targetHostSocket)
			
			try:
				inputsReady, outputsReady, errorsReady = select.select(inputs, outputs, [], 1.0)
			except Exception, e:
				print e
				break
				
			for inp in inputsReady:
				if inp == self.__clientSocket:
					try:
						data = self.__clientSocket.recv(4096)
					except Exception, e:
						print e
					
					if data != None:
						if len(data) > 0:
							targetHostData += data
						else:
							terminate = True
				elif inp == targetHostSocket:
					try:
						data = targetHostSocket.recv(4096)
					except Exception, e:
						print e
						
					if data != None:
						if len(data) > 0:
							clientData += data
						else:
							terminate = True
						
			for out in outputsReady:
				if out == self.__clientSocket and len(clientData) > 0:
					bytesWritten = self.__clientSocket.send(clientData)
					if bytesWritten > 0:
						clientData = clientData[bytesWritten:]
				elif out == targetHostSocket and len(targetHostData) > 0:
					bytesWritten = targetHostSocket.send(targetHostData)
					if bytesWritten > 0:
						targetHostData = targetHostData[bytesWritten:]
		
		self.__clientSocket.close()
		targetHostSocket.close()
		print "ClienThread terminating"

if __name__ == '__main__':
	if len(sys.argv) != 5:
		print 'Usage:\n\tpython SimpleTCPRedirector <host> <port> <remote host> <remote port>'
		print 'Example:\n\tpython SimpleTCPRedirector localhost 8080 www.google.com 80'
		sys.exit(0)		
	
	localHost = sys.argv[1]
	localPort = int(sys.argv[2])
	targetHost = sys.argv[3]
	targetPort = int(sys.argv[4])
		
	serverSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
	serverSocket.bind((localHost, localPort))
	serverSocket.listen(5)
	print "Waiting for client..."
	while True:
		try:
			clientSocket, address = serverSocket.accept()
		except KeyboardInterrupt:
			print "\nTerminating..."
			terminateAll = True
			break
		ClientThread(clientSocket, targetHost, targetPort).start()
		
	serverSocket.close()

@sivachandran chould this be modified to redirect the traffic to two servers instead of one? I am looking for a script that accept TCP/IP connections in a port and redirect the traffic to two different servers

@heisenberg2980 you can make targetHostSocket as an array of socket to redirect to multiple server. But you need to decided how you are going to respond, e.g., combine both server response. Also the termination condition needs to be updated to wait for any one or both server.

Thanks for the tips @sivachandran, I am afraid my python knowledge is not enough to be able to make those changes, and I am also surprised that I haven´t been able to find this TCP/IP duplication script already done anywhere, I think it would be really useful to be able to process data in different servers. In my case I am trying to receive data from a gps tracker and use it in two different servers, but I guess I will have to keep looking

@heisenberg2980 Reach out me through [email protected] if you need further assistance.

Thanks for the tips @sivachandran, I am afraid my python knowledge is not enough to be able to make those changes, and I am also surprised that I haven´t been able to find this TCP/IP duplication script already done anywhere, I think it would be really useful to be able to process data in different servers. In my case I am trying to receive data from a gps tracker and use it in two different servers, but I guess I will have to keep looking

You could parse the gps data and put it in a queue like redis pub/sub or mqtt in a format like json then let the two server listen to the queue